1. Field of the Invention
The invention relates to a control apparatus for an internal combustion engine. More particularly, the invention relates to a control apparatus for an internal combustion engine, which controls at least one of an intake valve and an exhaust valve.
2. Description of the Related Art
With respect to a related electromagnetically driven valve of an internal combustion engine, Japanese Patent Application Publication No. JP-A-2001-152881, for example, discloses an abnormality diagnosing device for an electromagnetically driven valve. The described abnormality diagnosing device compares the outputs of two lift sensors for intake valves or exhaust valves, which are simultaneously driven under the same driving conditions in each cylinder, and determines that an abnormality is present when the difference between the two sensor outputs exceeds a maximum allowable error.
In the structure described, however, a lift sensor is provided for each valve, which is disadvantageous in terms of cost.
On the other hand, if valve control is performed without using a lift sensor, the control may be inappropriately executed due to disturbances such as fluctuations that occur in vehicle load. Such disturbances significantly affect the optimal opening and closing of the exhaust valves in particular.